Transverse hairlines forming apparatus for stainless coil and stainless coil formed by the same

ABSTRACT

A transverse hairline forming apparatus includes a coil supporting unit to which a stainless steel coil is rotatably disposed; a coil winding unit spaced apart from the coil supporting unit, the coil winding unit holding and winding an end of the stainless steel coil; and at least one pair of surface treatment units disposed between the coil supporting unit and the coil winding unit, the at least one pair of surface treatment units configured to form transverse hairlines on a surface of the stainless steel coil perpendicular to a winding direction of the stainless steel coil. While the stainless steel coil is unwound and rewound on the coil winding unit, when the stainless steel coil passes below the at least one pair of surface treatment units, the at least one pair of surface treatment units form the transverse hairlines on the surface of the stainless steel coil.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

This application claims priority from Korean Patent Application No.10-2015-0123494 filed Sep. 1, 2015 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates to a stainless steel sheet havingtransverse hairlines that is used in a refrigerator. More particularly,the present disclosure relates to a transverse hairline formingapparatus for a stainless coil that can form transverse hairlines on asurface of a stainless steel sheet in a coil unit and a stainless steelcoil formed by the transverse hairline forming apparatus.

BACKGROUND

The refrigerators have been widely used as a home appliance for storingfood in a frozen state or chilled state.

In general, a refrigerator is provided with a main body that is formedin a substantially rectangular parallelepiped shape and a front surfaceof which is opened so that food can be stored, and a door formed to openand close a front opening of the main body.

These days, the refrigerators being used in households are recognized asa prop in the interior and are required to differentiate the exteriordesign of the refrigerator. In particular, when the refrigerator isinstalled, the door of the refrigerator is exposed to the outside sothat it is important to differentiate the design of the door of therefrigerator.

As an example of such a design, refrigerators the doors of which areformed of a stainless steel sheet so that unique sheen and texture ofthe stainless steel appear have been widely sold. In particular,recently, stainless steel sheets which are surface-treated so thathairlines appear on the surface thereof are used for the production ofthe refrigerator door.

Stainless steel sheets having vertical hairlines are widely used tomanufacture the refrigerator door. Here, the vertical hairlines refer toa surface treatment pattern formed in the height direction of therefrigerator.

In FIG. 1, a refrigerator 100 having a door 110 that is produced using astainless steel sheet with the vertical hairlines 111 is illustrated.

In the refrigerator door 110 that is produced of the stainless steelsheet with the vertical hairlines as illustrated in FIG. 1, thebrightness decreases and the irregular reflection occurs. In particular,as illustrated in FIG. 2, there is a problem that an irregularreflection phenomenon that is called as wave or smile occurs in theupper end portion of the refrigerator door.

This problem may be solved if the refrigerator door 110 is formed sothat transverse hairlines appear on the front surface of therefrigerator door 110. Here, the transverse hairlines refer to a surfacetreatment pattern formed in the width direction of the refrigerator 100.Accordingly, the transverse hairlines form a right angle with thevertical hairlines 111 as described above.

An example of a conventional hairline forming apparatus 200 for forminghairlines on the stainless steel sheet is illustrated in FIG. 3.

Referring to FIG. 3, a stainless steel coil 201 is rotatably mounted ona coil supporting unit 210, and an end of the stainless steel coil 201is fixed to a coil winding unit 220 that is disposed a predetermineddistance away from the coil supporting unit 210. Accordingly, when thecoil winding unit 220 is rotated, a strip-shaped stainless steel sheetconstituting the stainless steel coil 201 mounted on the coil supportingunit 210 is unwound, and rewound on the coil winding unit 220.

At this time, three grinding belts 230 are provided above a portion 203of the stainless steel coil 201 that extends between the coil supportingunit 210 and the coil winding unit 220. The three grinding belts 230 aredisposed perpendicular to a winding direction (the direction of arrow A)of the stainless steel coil 201, and each of the three grinding belts230 is rotatably supported by a pair of rollers. In detail, each of thethree grinding belts 230 is disposed so that the rotating direction (thedirection of arrow D) of the grinding belt 230 is parallel to thewinding direction (the direction of arrow A) of the stainless steel coil201.

Each of the grinding belts 230 is formed to have a width W1corresponding to a width W2 of the stainless steel coil 201.Accordingly, when the grinding belts 230 are rotated, hairlines areformed over the entire width of a portion 205 of the stainless steelcoil 201 that is in contact with the grinding belts 230. At this time,since the stainless steel coil 201 is continuously moved by the coilsupporting unit 210 and the coil winding unit 220, continuous hairlines207 are formed on the surface of the stainless steel coil 201 in thewinding direction (the direction of arrow A) of the stainless steel coil201. At this time, the hairlines 207 are formed parallel to the windingdirection (the direction of arrow A) of the stainless steel coil 201.

Accordingly, if the height H of the refrigerator door 110 is less thanthe width W2 of the stainless steel coil 201, it is possible to form therefrigerator door 110 by using the stainless steel coil 201 with thehairlines 207 formed in this way so that the transverse hairlines appearon the surface of the refrigerator door 110.

Side-by-side type of refrigerators, one-door type of refrigerators,built-in refrigerators, etc. that are widely used nowadays have a doorthe height of which is greater than 1250 mm.

However, since the maximum width of the stainless steel coil 201 that iscommonly used is 1250 mm, when the height H of the refrigerator door 110is greater than 1250 mm, the refrigerator door having the transversehairlines cannot be created by using the stainless steel coil 201provided with the hairlines 207 that are formed by using the hairlineforming apparatus 200 as illustrated in FIG. 3.

As a way to solve this problem, a method for manufacturing a steel sheetfor a refrigerator door (patent number; No. 10-0860645, Filing date;2007.05.04. Invention Title; a refrigerator, a steel sheet for arefrigerator door, and a method for manufacturing the same) has beenproposed.

In the method of manufacturing a steel sheet for a refrigerator door, astainless steel coil is cut to a length corresponding to the height ofthe refrigerator door, and then the transverse hairlines is formed bypolishing the surface of the cut stainless steel sheet.

However, when the transverse hairlines are formed on the stainless steelsheet provided by cutting the stainless steel coil to a predeterminedlength, the stainless steel sheets that are cut to a predeterminedlength need to be transported to post processes for manufacturing therefrigerator door. Accordingly, the feeding of the stainless steelsheets having the transverse hairlines into the post processes formaking the refrigerator door is expensive and the handling of thestainless steel sheets is difficult. This problem may be solved if thetransverse hairlines are formed on the stainless steel sheet in a coilstate and the stainless steel sheet having the transverse hairlines istransported in the coil state.

Accordingly, the development of a hairline forming apparatus which canform transverse hairlines in the coil state without cutting thestainless steel coil has been required.

SUMMARY

The present disclosure has been developed in order to overcome the abovedrawbacks and other problems associated with the conventionalarrangement. An aspect of the present disclosure relates to a transversehairline forming apparatus for a stainless steel coil that can formtransverse hairlines in a coil state without cutting a stainless steelcoil, and a stainless steel coil formed by the same.

According to an aspect of the present disclosure, a transverse hairlineforming apparatus for a stainless steel coil may include a coilsupporting unit to which a stainless steel coil is rotatably disposed; acoil winding unit spaced apart from the coil supporting unit, the coilwinding unit holding and winding an end of the stainless steel coil; andat least one pair of surface treatment units disposed between the coilsupporting unit and the coil winding unit, the at least one pair ofsurface treatment units configured to form transverse hairlines on asurface of the stainless steel coil perpendicular to a winding directionof the stainless steel coil, wherein, while the stainless steel coil isunwound from the coil supporting unit and then is rewound on the coilwinding unit, when the stainless steel coil passes below the at leastone pair of surface treatment units, the at least one pair of surfacetreatment units form the transverse hairlines on the surface of thestainless steel coil.

Each of the at least one pair of surface treatment units may include agrinding belt of a caterpillar shape; a drive roller disposed at an endof an inner side of the grinding belt, the drive roller to rotate thegrinding belt; a driven roller disposed at another end of the inner sideof the grinding belt, the driven roller to support the grinding belt tobe moved endlessly by the drive roller; and a working roller to cause aportion of the grinding belt to be in line contact with the surface ofthe stainless steel coil, the working roller to move between the driveroller and the driven roller to form the transverse hairlines.

The working roller may be disposed to reciprocate between a firstposition adjacent to the drive roller and a second position adjacent tothe driven roller.

The working roller may allow the portion of the grinding belt to be inline contact with the surface of the stainless steel coil when theworking roller moves from the first position to the second position.

The working roller of each of the at least one pair of surface treatmentunits may be disposed to move in opposite directions.

An abrasive grain size of the grinding belt of each of the at least onepair of surface treatment units may be different from each other.

The at least one pair of surface treatment units may include four pairsof surface treatment units, each of the four pairs of surface treatmentunits may include the grinding belt, and an abrasive grain size of thegrinding belt of at least one pair of the surface treatment units amongthe four pairs of surface treatment units may be different from theabrasive grain sizes of the grinding belts of other surface treatmentunits.

The stainless steel coil may include a stainless steel coil on a surfaceof which vertical hairlines are formed.

The stainless steel coil may include a stainless steel coil on a surfaceof which is embossing processed.

Other objects, advantages and salient features of the present disclosurewill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present disclosure willbecome apparent and more readily appreciated from the followingdescription of the embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a front view illustrating a refrigerator provided with a doormanufactured by using a stainless steel sheet having vertical hairlines;

FIG. 2 is a partially front view illustrating wave that appears on anupper end portion of the door of the refrigerator of FIG. 1;

FIG. 3 is a perspective view conceptually illustrating a conventionalhairline forming apparatus for a stainless steel coil;

FIG. 4 is a perspective view schematically illustrating a transversehairline forming apparatus for a stainless steel coil according to anembodiment of the present disclosure;

FIG. 5 is a partially perspective view illustrating a surface treatmentunit of the transverse hairline forming apparatus for a stainless steelcoil of FIG. 4;

FIGS. 6A, 6B, and 6C are partially cross-sectional views illustratingoperations of a working roller of a surface treatment unit of atransverse hairline forming apparatus for a stainless steel coilaccording to an embodiment of the present disclosure;

FIG. 7 is a perspective view illustrating a stainless steel coilmanufactured by a transverse hairline forming apparatus for a stainlesssteel coil according to an embodiment of the present disclosure;

FIG. 8 is a view illustrating a refrigerator including a door that ismanufactured by using a stainless steel sheet produced by a transversehairline forming apparatus for a stainless steel coil according to anembodiment of the present disclosure;

FIG. 9 is a partial view illustrating a refrigerator door that ismanufactured by using a stainless steel sheet produced by a transversehairline forming apparatus for a stainless steel coil according to anembodiment of the present disclosure; and

FIG. 10 is a partial view illustrating a refrigerator door that ismanufactured by using a stainless steel sheet produced by a transversehairline forming apparatus for a stainless steel coil according to anembodiment of the present disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION

Hereinafter, certain exemplary embodiments of a transverse hairlineforming apparatus for a stainless steel coil according to the presentdisclosure and a stainless steel coil manufactured by this transversehairline forming apparatus will be described in detail with reference tothe accompanying drawings.

The matters defined herein, such as a detailed construction and elementsthereof, are provided to assist in a comprehensive understanding of thisdescription. Thus, it is apparent that exemplary embodiments may becarried out without those defined matters. Also, well-known functions orconstructions are omitted to provide a clear and concise description ofexemplary embodiments. Further, dimensions of various elements in theaccompanying drawings may be arbitrarily increased or decreased forassisting in a comprehensive understanding.

The terms “first”, “second”, etc. may be used to describe diversecomponents, but the components are not limited by the terms. The termsare only used to distinguish one component from the others.

The terms used in the present application are only used to describe theexemplary embodiments, but are not intended to limit the scope of thedisclosure. The singular expression also includes the plural meaning aslong as it does not differently mean in the context. In the presentapplication, the terms “include” and “consist of” designate the presenceof features, numbers, steps, operations, components, elements, or acombination thereof that are written in the specification, but do notexclude the presence or possibility of addition of one or more otherfeatures, numbers, steps, operations, components, elements, or acombination thereof.

FIG. 4 is a perspective view schematically illustrating a transversehairline forming apparatus for a stainless steel coil according to anembodiment of the present disclosure, and FIG. 5 is a partiallyperspective view illustrating a surface treatment unit of the transversehairline forming apparatus for a stainless steel coil of FIG. 4. FIGS.6A, 6B, and 6C are partially cross-sectional views illustratingoperations of a working roller of a surface treatment unit of atransverse hairline forming apparatus for a stainless steel coilaccording to an embodiment of the present disclosure.

Referring to FIGS. 4 and 5, a transverse hairline forming apparatus fora stainless steel coil 1 according to an embodiment of the presentdisclosure may include a coil supporting unit 10, a coil winding unit20, and four pairs of surface treatment units 30-1, 30-2, 30-3, and30-4.

The coil supporting unit 10 is formed so that a stainless steel coil 11is rotatably mounted to the coil supporting unit 10. Here, the stainlesssteel coil 11 refers to a predetermined length of strip-shaped stainlesssteel sheet that is wound as illustrated in FIG. 7 and is used toproduce refrigerator doors. Accordingly, a single stainless steel coil11 is used to manufacture a plurality of refrigerator doors.

The coil winding unit 20 is disposed to be spaced apart a predetermineddistance from the coil supporting unit 10, and is formed to grasp andwind an end of the stainless steel coil 11 mounted to the coilsupporting unit 10. Accordingly, the coil winding unit 20 is providedwith a rotational shaft (not illustrated) that can grasp and rotate theend of the stainless steel coil 11. When the rotational shaft of thecoil winding unit 20 is rotated, the stainless steel coil 11 mounted tothe coil supporting unit 10 is unwound, and then is rewound on the coilwinding unit 20.

The coil supporting unit 10 and the coil winding unit 20 are formed asthe same as or similar to the coil supporting unit 210 and the coilwinding unit 220 of the conventional hairline forming apparatus 200;therefore, the detailed configuration thereof is omitted.

The four pairs of surface treatment units 30-1, 30-2, 30-3, and 30-4 aredisposed between the coil supporting unit 10 and the coil winding unit20, and form transverse hairlines 12 on the surface of the stainlesssteel coil 11 at right angles to a moving direction of the stainlesssteel coil 11, that is, in the winding direction (the direction of arrowA) of the stainless steel coil 11. In detail, while the stainless steelcoil 11 mounted to the coil supporting unit 10 is being unwound and thenis being rewound by the coil winding unit 20, the four pairs of surfacetreatment units 30-1, 30-2, 30-3, and 30-4 form the transverse hairlines12 on portions of the surface of the stainless steel coil 11 with whichthe four pairs of surface treatment units 30-1, 30-2, 30-3, and 30-4 arein contact, respectively. When the stainless steel coil 11 has passedthrough all of the four pairs of surface treatment units 30-1, 30-2,30-3, and 30-4, the transverse hairlines 12 are completed on the surfaceof the stainless steel coil 11.

Since each of the four pairs of surface treatment units 30-1, 30-2,30-3, and 30-4 includes two surface treatment units, the transversehairline forming apparatus for a stainless steel coil 1 according to anembodiment of the present disclosure as illustrated in FIG. 4 includes atotal of eight surface treatment units 31, 32, 33, 34, 35, 36, 37, and38. Hereinafter, for convenience of description, a surface treatmentunit that is closest to the coil supporting unit 10 among the eightsurface treatment units 31, 32, 33, 34, 35, 36, 37, and 38 is referredto as a first surface treatment unit 31, and the remaining surfacetreatment units are sequentially referred to as a second surfacetreatment unit 32, a third surface treatment unit 33, a fourth surfacetreatment unit 34, a fifth surface treatment unit 35, a sixth surfacetreatment unit 36, a seventh surface treatment unit 37, and an eighthsurface treatment unit 38 in the winding direction of the stainlesssteel coil 11. Accordingly, the surface treatment unit closest to thecoil winding unit 20 is the eighth surface treatment unit 38.

Also, the first and second surface treatment units 31 and 32 constitutea first pair of surface treatment units 30-1. The third and fourthsurface treatment units 33 and 34 constitute a second pair of surfacetreatment units 30-2. The fifth and sixth surface treatment units 35 and36 constitute a third pair of surface treatment units 30-3. The seventhand eighth surface treatment units 37 and 38 constitute a fourth pair ofsurface treatment units 30-4.

Since the eight surface treatment units 31, 32, 33, 34, 35, 36, 37, and38 are formed in the same structure, in the following, the structure ofthe eighth surface treatment unit 38 will be described in detail withreference to FIG. 5. The structure of each of the first to seventhsurface treatment units 31, 32, 33, 34, 35, 36, and 37 is the same asthe structure of the eighth surface treatment unit 38.

The eighth surface treatment unit 38 (hereinafter, referred to as asurface treatment unit) may include a grinding belt 41, a drive roller42, a driven roller 43, and a working roller 45.

The grinding belt 41 is formed in a caterpillar shape forming a closedcurve. The drive roller 42 and the drive roller 42 are disposed in theinner side of the grinding belt 41. The grinding belt 41 is disposedperpendicular to the winding direction (the direction of arrow A) of thestainless steel coil 11. Accordingly, the rotational direction (thedirection of arrow B) of the grinding belt 41 forms a right angle withthe winding direction (the direction of arrow A) of the stainless steelcoil 11.

The outer surface of the grinding belt 41 is provided with an abrasivewhich can process the surface of the stainless steel coil 11 so as toform the transverse hairlines 12. The grain size of the abrasive of thegrinding belt 41 may be approximate 80˜400 mesh.

The drive roller 42 is disposed at an end of the inner side of thegrinding belt 41, and generates a driving force to rotate the grindingbelt 41. The drive roller 42 may be formed as a built-in motorstructure. Alternatively, the drive roller 42 may be formed to berotated by receiving power from an outside motor as not illustrated.

The driven roller 43 is disposed at the other end of the inner side ofthe grinding belt 41, and supports the grinding belt 41 to be rotated bythe drive roller 42. Accordingly, when the drive roller 42 rotates, thegrinding belt 41 is supported and endlessly moved by the drive roller 42and the driven roller 43.

The working roller 45 is disposed between the drive roller 42 and thedriven roller 43 in the inner side of the grinding belt 41. The workingroller 45 is formed to cause a portion of the grinding belt 41 to be inline contact with the surface of the stainless steel coil 11 that passesbelow the grinding belt 41, thereby forming the transverse hairlines 12on the surface of the stainless steel coil 11. Accordingly, the entiresurface 41-1 (see FIGS. 6A, 6B, and 6C) of the grinding belt 41 facingthe stainless steel coil 11 is not in contact with the stainless steelcoil 11, but a portion 41-2 (see FIGS. 6A, 6B, and 6C) of the grindingbelt 41 which is pressed by the working roller 45 is in contact with thesurface of the stainless steel coil 11.

The working roller 45 is disposed to reciprocately move between thedrive roller 42 and the driven roller 43. In detail, if a position ofthe working roller 45 that is close to one side end of the stainlesssteel coil 11 adjacent to the drive roller 42 is referred to as a firstposition P1 and a position of the working roller 45 that is close to theother side end of the stainless steel coil 11 adjacent to the drivenroller 43 is referred to as a second position P2, the working roller 45is disposed to reciprocately move between the first position P1 and thesecond position P2. In other words, the working roller 45 is disposed toreciprocate linearly between the first position P1 adjacent to the driveroller 42 and the second position P2 adjacent to the driven roller 43.Accordingly, the moving direction (the direction of arrow C) of theworking roller 45 forms a right angle with the winding direction (thedirection of arrow A) of the stainless steel coil 11.

The working roller 45 may be disposed to be inclined by a predeterminedangle with respect to a virtual axis (hereinafter, referred to as avertical axis) parallel to the moving direction (the direction of arrowC) of the working roller 45 that is perpendicular to the windingdirection (the direction of arrow A) of the stainless steel coil 11 soas to form the transverse hairlines 12 perpendicular to the windingdirection (the direction of arrow A) of the stainless steel coil 11 on aportion of the moving stainless steel coil 11. An inclination angle ofthe working roller 45 with respect to the vertical axis may beappropriately determined according to a moving speed of the stainlesssteel coil 11, that is, a winding speed of the stainless steel coil 11,a moving speed of the working roller 45, etc. To this end, the workingroller 45 may be disposed so that a user can adjust the inclinationangle with respect to the vertical axis.

In the case that the working roller 45 is moved to form the transversehairlines 12 while the stainless steel coil 11 is moving, both when theworking roller 45 is moved from the first position P1 to the secondposition P2 and when the working roller 45 is moved from the secondposition P2 to the first position P1, the working roller 45 may be movedto cause the grinding belt 41 to maintain contact with the stainlesssteel coil 11.

At this time, the working roller 45 of each of the two surface treatmentunits 31-32, 33-34, 35-36, and 37-38 in the pair may be configured toperform a surface treatment operation while moving in the samedirection.

As another example, the working roller 45 of each of the two surfacetreatment units 31-32, 33-34, 35-36, and 37-38 in the pair may beconfigured to perform the surface treatment operation while moving inopposite directions to each other. For example, when the working roller45 of the eighth surface treatment unit 38 is positioned in the firstposition P1, the seventh surface treatment unit 37 that forms a pairwith the eighth surface treatment unit 38 is configured to be positionedin the second position P2. With this configuration, when the workingroller 45 of the eighth surface treatment unit 38 performs the surfacetreatment of the stainless steel coil 11 while moving from the firstposition P1 to the second position P2, the working roller 45 of theseventh surface treatment unit 37 performs the surface treatment whilemoving from the second position P2 to the first position P1.Accordingly, the working roller 45 of the seventh surface treatment unit37 and the working roller 45 of the eighth surface treatment unit 38perform the surface treatment moving in opposite directions to eachother, thereby forming the transverse hairlines 12.

The abrasive grain size of the grinding belt 41 of each of the eightsurface treatment units 31, 32, 33, 34, 35, 36, 37, and 38 may be formeddifferently. Alternatively, the abrasive grain size of the grinding belt41 of some of the eight surface treatment units 31, 32, 33, 34, 35, 36,37, and 38 may be formed identically.

Also, the abrasive grain sizes of the grinding belts 41 of the twosurface treatment units 31-32, 33-34, 35-36, and 37-38 in the pair maybe identically formed. For example, the grinding belts 41 of the firstand second surface treatment units 31 and 32 included in the first pair30-1 may be configured to have the same abrasive grain size. Further,the grinding belts 41 of the third and fourth surface treatment units 33and 34 included in the second pair 30-2, the grinding belts 41 of thefifth and sixth surface treatment units 35 and 36 included in the thirdpair 30-3, and the grinding belts 41 of the seventh and eighth surfacetreatment units 37 and 38 included in the fourth pair 30-4 may have thesame abrasive grain size, respectively.

The abrasive grain size of the grinding belt 41 of each of the fourpairs of surface treatment units 30-1, 30-2, 30-3, and 30-4 may bedefined within a certain range so that the transverse hairlines 12 arecompleted on the surface of the stainless steel coil 11 after passingthrough all of the four pairs of surface treatment units 30-1, 30-2,30-3, and 30-4.

For example, in the embodiment as illustrated in FIG. 4, the grindingbelts 41 of the first pair of surface treatment units 30-1 may have theabrasive grain size of about 80 to 120 mesh. The grinding belts 41 ofthe second pair of surface treatment units 30-2 may have the abrasivegrain size of about 80 to 120 mesh. The grinding belts 41 of the thirdpair of surface treatment units 30-3 may have the abrasive grain size ofabout 80 to 150 mesh. The grinding belts 41 of the fourth pair ofsurface treatment units 30-4 may have the abrasive grain size of about120 to 400 mesh.

At this time, the four pairs of surface treatment units 30-1, 30-2,30-3, and 30-4 may be configured to have a higher abrasive grain sizesequentially in the winding direction (the direction of arrow A) of thestainless steel coil 11. For example, the abrasive grain size of thegrinding belt 41 of the first pair of surface treatment units 30-1 maybe determined to be 90 mesh, the abrasive grain size of the grindingbelt 41 of the second pair of surface treatment units 30-2 may bedetermined to be 100 mesh, the abrasive grain size of the grinding belt41 of the third pair of surface treatment units 30-3 may be determinedto be 120 mesh, and the abrasive grain size of the grinding belt 41 ofthe fourth pair of surface treatment units 30-4 may be determined to be140 mesh.

Also, at least one pair of the four pairs of surface treatment units30-1, 30-2, 30-3, and 30-4 may be formed to have the abrasive grain sizedifferent from the abrasive grain size of the grinding belt 41 of theother pairs of surface treatment units. For example, the grinding belts41 of the first pair, the second pair, and third pair of surfacetreatment units 30-1, 30-2, and 30-3 may be configured to have the sameabrasive grain size, and only the grinding belt 41 of the fourth pair ofsurface treatment units 30-4 may be configured to have the abrasivegrain size higher than those of the grinding belts 41 of the three pairsof surface treatment units 30-1, 30-2, and 30-3.

The abrasive grain sizes of the grinding belts 41 of the four pairs ofsurface treatment units 30-1, 30-2, 30-3, and 30-4 may be properlydetermined depending on a kind of the stainless steel coil 11, a desiredstate of the transverse hairlines 12, a winding speed of the stainlesssteel coil 11, a moving speed of the working roller 45, a rotation speedof the grinding belt 41, etc.

The controller 50 controls the coil winding unit 20, and the driveroller 42 and working roller 45 of each of the eight surface treatmentunits 31, 32, 33, 34, 35, 36, 37, and 38. Accordingly, the controller 50may be configured to control the speed at which the coil winding unit 20winds the stainless steel coil 11, and the moving speed and the movingdirection of the working roller 45 and the rotation speed of the driveroller 42 of each of the eight surface treatment units 31, 32, 33, 34,35, 36, 37, and 38.

Although not illustrated in FIG. 4, a support member that supports aportion 13 of the stainless steel coil 11 which is located between thecoil supporting unit 10 and the coil winding unit 20 may be disposedbelow the stainless steel coil 11 between the coil supporting unit 10and the coil winding unit 20. The support member may be formed tosupport a force which is applied to the stainless steel coil 11 when thetransverse hairlines 12 are formed on the surface of the stainless steelcoil 11 by the working rollers 45 of the four pairs of surface treatmentunits 30-1, 30-2, 30-3, and 30-4, thereby preventing the stainless steelcoil 11 from sagging.

Hereinafter, operation of the transverse hairline forming apparatus forstainless steel coil 1 according to an embodiment of the presentdisclosure having the above-described structure will be described indetail with reference to FIGS. 4, 5, 6A, 6B, and 6C.

First, a stainless steel coil 11 to be processed is mounted to the coilsupporting unit 10, and an end of the stainless steel coil 11 mounted tothe coil supporting unit 10 is fixed to the coil winding unit 20. Whenoperating the coil winding unit 20 in this state, the stainless steelcoil 11 mounted to the coil supporting unit 10 is unwound, and thenrewound on the coil winding unit 20.

At this time, the transverse hairlines 12 are formed on the surface ofthe stainless steel coil 11′ being wound on the coil winding unit 20 bythe eight grinding belts 41 and working rollers 45 while the stainlesssteel coil 11 is passing below the four pairs of surface treatment units30-1, 30-2, 30-3, and 30-4.

In detail, after the working roller 45 presses the grinding belt 41 inthe first position P1 as illustrated in FIG. 6A so that a portion 41-2of the grinding belt 41 is in line contact with the stainless steel coil11, the working roller 45 is moved to the second position P2 asillustrated in FIG. 6C in a state in which the grinding belt 41 is inline contact with the stainless steel coil 11, and thus the transversehairlines 12 are formed on the surface of the stainless steel coil 11.FIG. 6B illustrates a state in which the working roller 45 is beingmoved, and the working roller 45 is located in approximately midwaybetween the first position P1 and the second position P2.

When the working roller 45 forms the transverse hairlines 12 whilemoving from the first position P1 to the second position P2, thegrinding belt 41 is rotated in one direction by the drive roller 42 sothat the grinding belt 41 which is positioned between the working roller45 and the stainless steel coil 11 also is moved. Accordingly, while theworking roller 45 is moving from the first position P1 to the secondposition P2, a portion 41-2 of the grinding belt 41 that is in contactwith the stainless steel coil 11 is continuously changed to form thetransverse hairlines 12 on the surface of the stainless steel coil 11.Accordingly, since the surface treatment of the stainless steel coil 11is performed by the portion 41-2 of the grinding belt 41 which iscontinuously changed, the transverse hairlines 12 may be effectivelyformed.

After the working roller 45 arrives at the second position P2, theworking roller 45 moves back to the first position P1, and causes thegrinding belt 41 to be in line contact with the stainless steel coil 11,thereby forming the transverse hairlines 12.

As illustrated in FIG. 4, since the transverse hairline formingapparatus for a stainless steel coil 1 according to an embodiment of thepresent disclosure is configured so that the four pairs of surfacetreatment units 30-1, 30-2, 30-3, and 30-4 are provided with thegrinding belts 41 the abrasive grain sizes of which are higher insequence, the desired transverse hairlines 12 are completed after thestainless steel coil 11 is moved in the winding direction (the directionof arrow A) and passes by the fourth pair of surface treatment units30-4.

Accordingly, in the transverse hairline forming apparatus for astainless steel coil 1 according to an embodiment of the presentdisclosure, while the coil winding unit 20 is winding the stainlesssteel coil 11, the transverse hairlines 12 are continuously formed onthe surface of the stainless steel coil 11 by the eight surfacetreatment units 31, 32, 33, 34, 35, 36, 37, and 38.

In the transverse hairline forming apparatus for a stainless steel coil1 according to an embodiment of the present disclosure, when rewindingthe stainless steel coil 11 mounted on the coil supporting unit 10 onthe coil winding unit 20 is completed, the processing of the transversehairlines 12 on the surface of the strip-shaped stainless steel sheet toform the stainless steel coil 11 is completed. Accordingly, thestainless steel coil 11′ provided with the transverse hairlines 12 asillustrated in FIG. 7 may be obtained.

In the above description, the eight surface treatment units 31, 32, 33,34, 35, 36, 37, and 38 form the transverse hairlines 12 on the surfaceof the stainless steel coil 11 while the stainless steel coil 11 isstill wound. However, as another embodiment, the transverse hairlines 12may be formed in a state in which the stainless steel coil 11 isstopped.

In the case of the present embodiment, the configuration of a transversehairline forming apparatus for a stainless steel coil is the same asthat of the transverse hairline forming apparatus for a stainless steelcoil 1 as illustrated in FIG. 4, but the control method thereof isdifferent. Also, in the case of this embodiment, because the transversehairlines 12 are formed in a state in which the stainless steel coil 11is stationary, the working roller 45 is disposed parallel to the windingdirection (the direction of arrow A) of the stainless steel coil 11.

The controller 50 controls the coil winding unit 20 so that the coilwinding unit 20 intermittently operates to wind a predetermined lengthof the stainless steel coil 11 and then stops.

For example, in the state in which the stainless steel coil 11 isstationary, the controller 50 controls the eight surface treatment units31, 32, 33, 34, 35, 36, 37, and 38 so that the drive rollers 42 arerotated to cause the grinding belts 41 to perform the endless movementand the working rollers 45 are moved from the first position P1 to thesecond position P2. Thus, the grinding belt 41 is in line contact withthe surface of the stainless steel coil 11 by the working roller 45,thereby forming the transverse hairlines 12 on the surface of thestainless steel coil 11.

When the working roller 45 arrives at the second position P2, thecontroller 50 stops the rotation of the drive roller 42, and thenreturns the working roller 45 to the first position P1. At this time,the working roller 45 is lifted a certain distance to be prevented frompressing the grinding belt 41 against the stainless steel coil 11.Accordingly, when the working roller 45 is returned from the secondposition P2 to the first position P1, the transverse hairlines 12 arenot formed.

When the working roller 45 is moved from the second position P2 to thefirst position P1, the controller 50 controls the coil winding unit 20to wind the stainless steel coil 11 a predetermined length. At thistime, the predetermined length of the wound stainless steel coil 11 is alength of the stainless steel coil 11 on which the transverse hairlines12 are formed by the eighth surface treatment unit 38. The length may beapproximately equal to the width W3 of the grinding belt 41.

After winding the stainless steel coil 11 the predetermined length bycontrolling the coil winding unit 20, the controller 50 stops the coilwinding unit 20 so that the stainless steel coil 11 is not moved. Afterthat, the controller 50 again controls the drive rollers 42 and theworking rollers 45 to form the transverse hairlines 12 on the surface ofthe stainless steel coil 11.

The controller 50 may repeat the surface treatment operation and thewinding operation of the stainless steel coil 11 as described above tocontinuously form the transverse hairlines 12 on the surface of thestainless steel coil 11.

In the above description, the transverse hairlines 12 are processed onthe surface of the stainless steel coil 11 by using the four pairs ofsurface treatment units 30-1, 30-2, 30-3, and 30-4, that is, the eightsurface treatment units 31, 32, 33, 34, 35, 36, 37, and 38. However,this is only one example. The transverse hairline forming apparatus fora stainless steel coil 1 according to an embodiment of the presentdisclosure may be configured to form the transverse hairlines 12 usingat least one pair of surface treatment unit, that is, at least twosurface treatment units or five or more pairs of surface treatmentunits, that is, ten or more surface treatment units.

With the transverse hairline forming apparatus for a stainless steelcoil 1 according to an embodiment of the present disclosure as describedabove, because the transverse hairlines 12 can be formed on thestrip-shaped stainless steel sheet without cutting the stainless steelcoil 11, it is possible to obtain a stainless steel coil 11′ on thesurface of which the transverse hairlines 12 are formed. Accordingly,because the stainless steel sheet to be a basic plate of therefrigerator door can be moved in a coil unit for the post processes formanufacturing the refrigerator door, for example, an additional surfacetreatment process, a molding process, etc., the transportation is moreconvenient, the handling is easier, and the logistics cost is reducedcompared to the prior art in which the cut stainless steel sheets withthe transverse hairlines are transported.

A side by side type of refrigerator 300 provided with a door 310 whichis manufactured using the stainless steel coil 11′ as illustrated inFIG. 7 on which the transverse hairlines 12 are formed by the transversehairline forming apparatus for a stainless steel coil 1 according to anembodiment of the present disclosure is illustrated in FIG. 8.

Referring to FIG. 8, on the surface of the door 310 of the refrigerator300, the transverse hairlines 12 are formed in a width direction of therefrigerator 300. When the transverse hairlines 12 are formed on thesurface of the door 310 of the refrigerator 300 as described above, theirregular reflection phenomenon, which is called as wave, smile, and thelike, may not occur in the upper end portion of the door 310 differentlyfrom the refrigerator door 110 having the vertical hairlines 111 asillustrated in FIG. 1.

In the above description, the transverse hairline forming apparatus fora stainless steel coil 1 according to an embodiment of the presentdisclosure forms the transverse hairlines 12 on the surface of thestainless steel coil 11 in which there is no pattern.

However, the transverse hairline forming apparatus for a stainless steelcoil 1 according to an embodiment of the present disclosure may form thetransverse hairlines on the surface of the stainless steel coil on whicha pattern is formed.

For example, the transverse hairlines may be formed on the stainlesssteel coil 201 on which the vertical hairlines 207 are formed by theconventional hairline forming apparatus 200 of FIG. 3 using thetransverse hairline forming apparatus for a stainless steel coil 1according to an embodiment of the present disclosure. So, a pattern inwhich the vertical hairlines and the transverse hairlines cross eachother may be obtained.

An example of a refrigerator door 310′ having the pattern in which thetransverse hairlines and the vertical hairlines cross is illustrated inFIG. 9.

As another example, the transverse hairline forming apparatus for astainless steel coil 1 according to an embodiment of the presentdisclosure may form the transverse hairlines on the surface of astainless steel coil on which an embossing pattern is formed by anembossing process. Thus, a pattern in which the embossing pattern iscombined with the transverse hairlines may be obtained.

An example of a refrigerator door 310″ having the pattern in which theembossing pattern is combined with the transverse hairlines isillustrated in FIG. 10. However, the embossing pattern as illustrated inFIG. 10 is only one example. A variety of embossing patterns may beapplied to the refrigerator door.

While the embodiments of the present disclosure have been described,additional variations and modifications of the embodiments may occur tothose skilled in the art once they learn of the basic inventiveconcepts. Therefore, it is intended that the appended claims shall beconstrued to include both the above embodiments and all such variationsand modifications that fall within the spirit and scope of the inventiveconcepts.

What is claimed is:
 1. A transverse hairline forming apparatus for astainless steel coil, the transverse hairline forming apparatuscomprising: a coil supporting unit to which a stainless steel coil isrotatably disposed; a coil winding unit spaced apart from the coilsupporting unit, the coil winding unit holding and winding an end of thestainless steel coil; and at least one pair of surface treatment unitsdisposed between the coil supporting unit and the coil winding unit, theat least one pair of surface treatment units configured to formtransverse hairlines on a surface of the stainless steel coilperpendicular to a winding direction of the stainless steel coil,wherein, while the stainless steel coil is unwound from the coilsupporting unit and then is rewound on the coil winding unit, when thestainless steel coil passes below the at least one pair of surfacetreatment units, the at least one pair of surface treatment units formthe transverse hairlines on the surface of the stainless steel coil. 2.The transverse hairline forming apparatus of claim 1, wherein each ofthe at least one pair of surface treatment units comprises, a grindingbelt of a caterpillar shape; a drive roller disposed at an end of aninner side of the grinding belt, the drive roller to rotate the grindingbelt; a driven roller disposed at another end of the inner side of thegrinding belt, the driven roller to support the grinding belt to bemoved endlessly by the drive roller; and a working roller to cause aportion of the grinding belt to be in line contact with the surface ofthe stainless steel coil, the working roller to move between the driveroller and the driven roller to form the transverse hairlines.
 3. Thetransverse hairline forming apparatus of claim 2, wherein the workingroller is disposed to reciprocate between a first position adjacent tothe drive roller and a second position adjacent to the driven roller. 4.The transverse hairline forming apparatus of claim 3, wherein theworking roller allows the portion of the grinding belt to be in linecontact with the surface of the stainless steel coil when the workingroller moves from the first position to the second position.
 5. Thetransverse hairline forming apparatus of claim 3, wherein the workingroller of each of the at least one pair of surface treatment units isdisposed to move in opposite directions.
 6. The transverse hairlineforming apparatus of claim 2, wherein an abrasive grain size of thegrinding belt of each of the at least one pair of surface treatmentunits is different from each other.
 7. The transverse hairline formingapparatus of claim 1, wherein the at least one pair of surface treatmentunits comprises four pairs of surface treatment units, each of the fourpairs of surface treatment units comprises a grinding belt, and anabrasive grain size of the grinding belt of at least one pair of thesurface treatment units among the four pairs of surface treatment unitsis different from the abrasive grain sizes of the grinding belts ofother surface treatment units.
 8. The transverse hairline formingapparatus of claim 1, wherein the stainless steel coil comprises astainless steel coil on a surface of which vertical hairlines areformed.
 9. The transverse hairline forming apparatus of claim 1, whereinthe stainless steel coil comprises a stainless steel coil on a surfaceof which is embossing processed.
 10. A stainless steel coil comprising:a surface on which transverse hairlines are processed by a transversehairline forming apparatus for a stainless steel coil, wherein thetransverse hairline forming apparatus for a stainless steel coilcomprises, a coil supporting unit to which a stainless steel coil isrotatably disposed; a coil winding unit spaced apart from the coilsupporting unit, the coil winding unit holding and winding an end of thestainless steel coil; and at least one pair of surface treatment unitsdisposed between the coil supporting unit and the coil winding unit, theat least one pair of surface treatment units configured to formtransverse hairlines on a surface of the stainless steel coilperpendicular to a winding direction of the stainless steel coil,wherein, while the stainless steel coil is unwound from the coilsupporting unit and then is rewound on the coil winding unit, when thestainless steel coil passes below the at least one pair of surfacetreatment units, the at least one pair of surface treatment units formthe transverse hairlines on the surface of the stainless steel coil.